If you use a wide angle lens, you should be okay without a filter. The filter is really only necessary for telephoto style lenses. With a wide angle lens, like on your smart phone, there won't be enough light coming through to damage the sensor or film. Think about how many people have taken photos of sunsets or sunrises with the Sun in frame.
As for which type of film, I'd say use whatever you like best. The Sun is the purest form of white light around, so it's gonna have light in all parts of the spectrum. One film won't necessarily be better than another, just different (slightly). I'm bringing along some Rollei IR and Kodak Ektar. I'll also bring some Velvia 100 and some TMAX 100 just incase, but plan on using them more for other stuff than direct Sun shots.
If you're really concerned, you might check out what the astrophotography guys use. After all, the Sun is just a star. But I don't think that would matter much in this case, because those guys are trying to pick up the faintest traces of light, and we're going to be trying to pick up billions of times more!